Alloy



Patented Sept. 3,

f PATENT OFFICE ALLOY Anthony G. .de Goly er, NewYork, N. Y.

- No Drawing. Applicationlilay 28,1938,

Serial 80,210,768

, dclaims.

The present invention relates to a new anduseful alloy and relates particularly to an alloy containing'as essential components boron, zir-' conium, tungsten, chromium, iron and cobalt.

This application is a continuation in part of my co-pending application Serial No.-1l5,81 6, died December 14, 1936, whichin turn is a continuation in part of my application Serial No. 20,050, filed May 6, 1935, the subject matter common to all of theseapplications being now claimed herein.

An object of the present invention is to provide an alloyhaving certain inherent physical properties and characteristics which can be developed and controlled by means of thermal treatment. Another object is to provide an alloy which can be manufactured in finished or semiflnished forms by means of centrifugal casting.

The alloy of the present invention has a combination of physical properties and characteristics which render it especially valuable for use as metal cutting tools and many other industrial purposes.

I have found that the alloy disclosed herein cannot be economically forged or rolled, as it is particularly resistant to deformation at both I have also.

alloy by means of ordinary sravlty casting. I'

have discovered, however, thatcastforms'possessing valuable p sical properties can be produced by casting the alloy under pressureand especially by means of centrifugal casting. By means of the latter method the grain size and density of the alloy can be closely'controlled through the regulation of certain conditions of v .the casting operation.

I have found through experiment that by alloying or otherwise intimately combining boron,;

metal from the group 'zirconium and, titanium,

metal from the group; tungsten, molybdenum and ing parts of internal combustion motors and many other purposes. One distinctive and advantageous characteristic. of the present composition is that it is well adapted for the manufacture of cast forms by means of centrifugal casting. Another advantage is that such cast forms are readilyamenable to thermal treatment for the improvement and. control of important physical properties; I t

I have found that when the present composition is cast by any of the usual gravity casting methods that the castings do not have the proper density to render the forms commercially satisfactory. m

I have also found that in general the physical .structure of. the castings produced by gravity methods is such as to make alloys more or less unsuitable for metal cutting tools and many other applications. I have discovered that by u applying suitable pressure to the molten metal while it is in the mold that cast forms can be produced having a relatively high densityand the requisite physical structure. I have found that'while various methods may be used for .de-

veloping the desired degree of pressure on the molten metal that centrifugal casting offers av satisfactory and economical means of manufacturing cast forms of the present composition.

Cast bodies of the alloy produced by centrifu- 25 gal casting may be utilized in the as cast condition. However, I usually prefer to subject the castings to a suitable thermal treatment before I using them for metal cutting tools and many other purposes.

I have found by research that the preferred structure of an aggregate of the present composition comprises at least two principal constituentsz' (a) A relatively hard intermetallic compound of boron with one or more of the essens5 tial components; and '(b) a solid solutionof two or more of the essential components, which has a lower degree of hardness and functions as a matrix. For many uses an appreciable percentage of the intermetallic boron compound should 40 be in the form of more or lessflnely divided particles dispersed throughout'the matrix; An aggregate having the preferred physical structure possesses a combination of essential physical properties superior to the properties of a cast aggregate which has not been subjected to thermal treatment. t

The present alloy is characterized by being amenable to thermal treatment for the developmerit of precipitation hardening. As an illustration, one satisfactory method is to heat a cast aggregate of "the alloy-at a temperature'exceeding approximately 1000 C. for a period of time sufficient to effect dissolution of a substantial portion of the boron containing segregate in. the

matrix metal. In general, it is not essential that the entire aggregate be converted into a solid solution. The alloy is quenched or cooled from the primary heating temperature in such a manner as to retain substantially all of the solidsolution formed during the primary heating. .The

hardness of the composition will then be materialiy lower than that of the original casting.

' In this condition the material may be ground,

shaped or otherwise worked as may be desired. The body of the alloy can subsequently be heated at a temperature some 300 to 500 C. lower than the temperature of the primary heating. Such secondary heating will result in the precipitation of finely divided boron containing constituents from the solid solutiomand an increase in hardness.

' By regulating the temperature and time of the high hardness, e. 63 to '70 Rockwell C, and high resistance to impact. Another important property is'that virtually all of the degrees of hardness and resistance to impact developed by thermal treatment-are retained when the alloy is subjected to temperatures up to approximately 600 C.

purity incide Although I usually prefer to have the alloy composed substantially of boron, zirconium, tungsten, I

chromium, iron and cobalt within the percentages specified herein, I have found that the tungsten cambe supplanted in whole or in part by molybdenum, uranium or both.

I have also found that in this alloy the effect of zirconium and titanium are the same so far as I have been able to observe, and consequently, either of these elements may be used to supplant the other in whole or in part.

Specific examples of the compositions within the scope of the present invention which I have.

found valuable for numerous industrial purposes are the following: Boron 1.20%, titanium 0.65%, tungsten, 14%, chromium 5%, iron cobalt substantially the balance; boron 1.65%, zirconium 1.30%, tlmgsten 19%, chromium 4%, iron 15%, cobalt substantially the balance; boron 1.80%, titanium 0.75%, molybdenum 14%, chromium 7%, iron 27%, cobalt substantially the balance; boron 1.10%, titanium 0.35%, tungsten 5%, molybdenum 12%, chromium 6%, iron 22%, co-

, bait. substantially the balance.

I prefer to have the alloys of the present invention substantially free from carbon in order to avoid all of the disadvantages associated with'alloys or compositions containing appreciable amounts of carbon, particularly when such alloys are used for metal cutting tools. I have found, however, that certain of the metals and, alloys used in producing the compositions of the present invention generally contain varying amounts of carbon as an impurity and, consequently, the 'alloys of the present invention'will usually contain small amountsiof. carbon in the nature of an imf t c-manufacture. It is essential to restrict 7th amount of carbon so present to amounts the physical properties. I have found that amounts of carbon in excess of approximately 0.30% apparently act to embrittle the alloy and also to inhibit the desired and necessary physical reactions during thermal treatment.

I have also found that-materials used in producing this alloy frequently contain other elements more or less in the nature of impurities,

such, for example, as manganese, silicon and aluof the alloy.

It will be evident, therefore, that the composition of the present invention comprises the following essential components: Boron 0.25% to 5%, metal selected from the group zirconium and titanium 0.25% to 7%, metal selected from thegroup tungsten, molybdenum and uranium 5%,-to 30%, chromium 1%, to 25%, iron 5% to 40%, and

. the balance substantially cobalt.

I claim:

' 1. As a new article of manufacture, a centrifugally cast form of. an alloy comprising metal selected from the group consisting of tungsten, molybdenum and uranium 5% to boron 0.25% to 5%, metal selected from the group consisting of zirconium and titanium 0.25% to 7%, chromium 1% to 25%, iron 5% to and the balance cobalt except for minor amounts-of incidental impurities in which carbon does not exceed approximately 0.30%; said cast form bein characterized by a-relatively .fine and uniform grain structure, and being further characterized by being responsive to thermal treatment for precipitation hardening.

2. As a new article of manufacture, a centrifugally cast form of an alloy comprising metal selected from the group tungsten, molybdenum and uranium 5% to 30%,boron 0.25% to 5%, zirconium 0.25% to 7%, chromium 1% to 25%, iron 5% to. 40% and the balance cobalt except for minor amounts 'of' incidental impurities in which carbon does not exceed approximately 0.30%; said cast form being characterized by a relatively fine and'uniform grain structure, and being further characterized by being responsive to thermal treatment forprecipitation hardening.

3. As a. new article of manufacture, a centrifugally cast form of an alloy comprising tungsten 5% to 30%, boron 0.25% to 5%, zirconium 0.25% to 7%, chromium 1% to 25%, iron 5% to 40% and the balance cobalt except for minor amounts of incidental impurities in which carbon does not exceed approximately 0.30%; said cast form being characterized by a relatively fine and uniform grain structure, and being further characterized by being responsive to thermal treatment for precipitation hardening.

4. As a new article of manufacture, a centrifugally cast form of an alloy comprising molybdenum 5% to 30%, boron 0.25% to 5%, zirconium 0.25% to 7%, chromium 1% to 25%, iron 5% to 1 40% and the balance cobalt except for minor incidental impurities in which carbon does not exceed, approximately 0.30% said cast form being characterized by a relatively fine and uniform grain structure, and being further characterized by being responsive to thermal treatment for precipitation hardening.

ANTHONY G. on GOLYER.

which not be advrselyicffective-on 

